Back in 1985, a Chesapeake Bay (USA) wetland - sustaining both pure and mixed stands of the C4 grass Spartina patens and the C3 sedge Scirpus olneyi - was selected for an open-top chamber study of the effects of full-day (24-hour) atmospheric CO2 enrichment to 340 ppm above the then-ambient concentration of the same value. And now, in a paper published 28 years later in Global Change Biology, the director of the project summarizes some of the important findings of this unique and unparalleled undertaking. So what has been learned from this longest of all such studies?

Advising us that "the question of whether rising atmospheric CO2 will cause the land sink for anthropogenic carbon to expand or contract has been the basis for most ecosystem studies to date," Drake writes that we now have, from the Chesapeake Bay study, "strong evidence that shoot and root biomass and net ecosystem production increased significantly" under real-world conditions of growing fossil fuel usage. And he thus infers - from the fact that (1) methane emission (Dacey et al., 1994) and (2) nitrogen fixation were also stimulated by elevated CO2 (Dakora and Drake, 2000), and that (3) inputs of soil carbon also increased - that "ecosystems will accumulate additional carbon as atmospheric CO2 continues to rise, as suggested by Luo et al. (2006)."

In a closely related matter, Drake also writes that the long duration of the Chesapeake Bay wetland study allows for a test of "the idea that some process, such as progressive nitrogen limitation, may constrain ecosystem responses to elevated CO2 in native ecosystems." But his and his associates' findings, as well as those of Norby et al. (2005) and Norby and Zak (2011), imply, as he notes, that quite to the contrary, Earth's ecosystems will continue to accumulate carbon as the air's CO2 content continues its upward trajectory.

Thus we find clear evidence from data obtained in the real world of important benefits conferred by rising atmospheric CO2 upon nature, evidence that many unfortunately continue to deny.